Board for demonstrating electric circuits



Sept. 18, 1951 c. E. BALLARD 2,568,535

BOARD FOR DEMONSTRATING ELECTRIC CIRCUITS Filed April 10, 1945 5 Sheets-Sheet 1 Sept. 18, 1951 c. E. BALLARD 2,568,535

BOARD FOR DEMONSTRATING ELECTRIC CIRCUITS Filed April 10, 1945 5 Sheets-Sheet 2 PIC-3.5.

CHARLS BALLARD Sept. 18, 1951 C. E. BALLARD BOARD FOR DEMONSTRATING ELECTRIC CIRCUITS Filed April 10, 1945 5 Sheets-Sheet 5 mwwkm, CZHFCRLES 1E1 BBLLPCRTD Sept. 18, 1951 c. E. BALLARD BOARD FOR DEMONSTRATING ELECTRIC CIRCUITS 5 Sheets-Sheet 4 Filed April 10, 1945 Sept. 18, 1951 Filed April 10, 1945 C. E. BALLARD BOARD FOR DEMONSTRATING ELECTRIC (EIRCUITS 5 Sheets-Sheet 5 FIG. B

8 CHARLES E. BALLIR nuinvim Patented Sept. 18, 1951 BOARD FOR DEMONSTRATING ELECTRIC CIRCUITS Charles E. Ballard, Ogden, Utah Application April 10, 1945, Serial No. 587,583

2 Claims.

This invention relates primarily to an educational device and particularly to a board for demonstrating electrical circuits.

The present board is designed especially to serve as an aid in teaching the theory and prac tice of radio, radar, television and allied electronic devices and an object of the present invention is to provide a board or panel which possesses versatility or flexibility in the sense that a multitude of different types of circuits, particularly electronic circuits, can be formed or set up thereon with great rapidity.

Since electronic tube circuits fundamentally comprise an electronic tube or tubes, plus certain associated parts or instrumentalities, a further object of the invention is to provide a board or panel having a multiplicity of electric contacts or terminals thereon so arranged with respect to one or more multi-terminal tube sockets that each socket and its associated contacts constitutes a unit which may be used alone or in conjunction with one or more other units, depending upon the size of the board and the number of units provided thereon. In this way, the flexibility of the board is materially increased.

With these and other objects, the invention consists in certain details of construction and combinations and arrangements of parts, all as will hereinafter be more fully described and the novel details thereof particularly pointed out in the appended claims.

In the accompanying drawings Figure 1 is a diagrammatical illustration of -a board or panel embodying what is at present believed to be the preferred form of the present invention;

Figs. 2, 2 and 2 are top, side and end views, respectively, of a transformer assembly for use on the board;.

Figs. 3, 3 and 3 are top, side and end views, respectively, of a resistor unit assembly;

Figs. 4, 4 and 4 are top, side and end views, respectively, of an inductor assembly;

Fig. 5 is a top plan view of a section'of the board, illustrating a series of three contacts in the form of sockets;

Fig. 5* is a side elevation and Fig. 5 is an end elevation of the panel section shown in Fig. 5.

Figs. 6 and 6 are diagrammatical views illustrating one circuit that can be set up on the board involvin two units; and

Figs. '7 and 7 are diagrammatical views illustrating a circuit which involves only one unit of the board. 1

Preferably, the board is of the multi-unit type and each unit may be described as consisting of a tube socket, a band of primary contacts arranged in groups around the socket with one contact of each group connected to a socket terminal, positive and negative power lines with multiple terminals arranged around or encircling but spaced from said primary contacts, and a band of connector contacts intermediate to said primary contacts and power lines, all of said contacts and power line terminals being so arranged that by the use of various component parts or instrumentalities to be later described, connections can be established from the tube socket to the power lines. In addition to this basic ar rangement for the individual unit, additional contacts are provided on the multi unit board to facilitate the establishment of interconnecting circuits between different units or from one section of the board to another remotev section and a still further line of contacts is provided between each two units whereby connections may be established directly across the board between the interconnecting circuit lines at opposite sides thereof.

For. instance, in the two-unit board illustrated in Figure 1 there are two multi-terminal tube sockets 30, 30 one for each unit and in the board described, each is adapted to receive a tube of the octal type. In using anoctal tube socket such as illustrated, two terminals I02, I01 of each socket are connected to two contacts 33, 34 by wires (not shown), one wire extending from contact 33 to the socket terminals I02 and the other wire running from contact 34 to socket terminals I01. These contacts 33, 34 are adapted to be connected to a feed line which will supply a current of proper voltage (approximately 6.3 volts A. C.) to light the filaments or heaters of tubes placed in the sockets. Of course, it will be understood that the terminals of the tube socket which are connected to contacts 33, 34, will vary depending upon the type of tube used. Immediately surrounding each socket are the socalled primary. contacts 35, 36, 31, 38, 39, 40, each adapted to be connected by wires (not shown) to one of the terminals of its associated tube socket, depending upon the number of pins carried on the bases of the tubes used in the sockets. Each primary contact is connected to additional contacts 4| which are arranged on the board in various patterns to facilitate the assembly of component partsin desired circuits as will later be described. Contacts 35 and 39 each have two additional contacts 41 associated therewith in a straight line; contacts 36 each have three additional contacts 4| associated therewith in L-shaped arrangements; contacts 3? each have three contacts 41 connected thereto in the form of a horizontally disposed T; contacts 38 and 40 each have four contacts 4| associated therewith in oppositely reversed L formations. Thus, there is provided a band of connected primary contacts surrounding the tube socket of each unit". The two primary contacts E09, Iii}, associated with each socket are also connected to additional contacts 4|, but as the present description is based on the use of an octal tube these two primary contactsare not Wired to any of the socket terminals.

Extending around the board are the positive and negative power lines 42, d3 forsuppl yi ng a direct current of approximately- 250 volts. The positive line 42 has a multiplicity of contacts or terminals M provided thereon and the negative line 43 is similarly provided with a plurality of contacts or terminals 45.

. The primary contacts are adaptedtobe connected to desired contacts or terminals in these power lines but, to. lend flexibility of usage to the. board, this connection is not made direct but throu hv aband ofso called connector contacts Mi interposed between positive power line 42 and the band otprimarycon-tacts. As the board and its entire assembly of contacts preferably takes a substantially rectan ular. shape these so-called connector contacts whichare connected together in alined groups of three in mostinstances, may be generally describedasbeing disposed at right angles. to the contiguous. portion of the positive power line 42.. Itwill' alsobe observed that the various contacts, including the power line terminals. are arranged. in rows transversely and lengthwise of the board and .tofac'ilitate designation of any particular contact. these rows are numberedlto 23 lengthwiseof the board and-lettered A.to Q crosswise of. the board. Using these designating numerals and letters, particular at.- tention. is called to the: twelfth row of contacts. It will be observed that this particular row. is. locatedata. line medial of. the. tube sockets 30,. 3'0 and might. be described. as. dividing. the board into the two units previously mentioned. In this connection,. means. are provided for facilitating interconnections between'the two units, or from one point. of the board to another point remote therefrom. Thesemeans consist of two interconnector lines. 51,148, which extend lengthwise orthe board the full. length ofthe two units, Each of these interconnector lines 41, 48', are provided withcontacts 49 atthe. end's ofthe board and-with. contacts 50 centrally of the two units, these contacts 5.0.being located in the medial line of contacts I2.. previously mentioned.- In addition, other contacts 5131 may be provided in line 4% intermediate its centrally located contacts 50 and the endsof. said lines so .as to facilitate connecting. various portions of. either unit to a larger selectionof contacts 46'. Inother words, these.

interconnector lines 41, 48 with their associated contacts. 49, -02 and. 50s. render still greater flexibility in. the use of the board.

' It. will be appreciatedthatthe boardmay be reduced to a single unit'by omitting one of'the sockets and its associated. primary contacts and connectorcontacts while, on the other hand, additional units may be added by duplicating these individual units on the board.

In the use ofthe board, circuits of various types, as previously mentioned, can be built up or established, depending upon the component parts that aroused therein-and the arrangement of those parts on the board. Preferably, as shown in Figs. 5, 5 and 5 the various contacts are all preferably in the form of so-called banana jacks, indicated at 50, which are adapted to be threaded into the board 5| and which have the usual sockets to permit the component parts or electrical devices to be plugged into them. Also, as shown in Fig. 1, all of these banana jacks or contacts are equi-distantly spaced. from one another, both transversely and longitudinally of the board so that electrical devices of various types can be used therein so long as the plugs otsaiddevices are spaced apart a. unit of length, ors-a multiple thereof corresponding to the unit of length by which the banana jacks are spaced from one another. For instance, a transformer I8 isillustratedinFigs. 2, 2 and 2 As shown in Fig. 2, the base 19 of the transformer has four plugs 12 depending therefrom, one at each corner of the base. As shown: in Figs. 2 and 2 these plugs l2'arespaced laterally of the transformer basefla distance corresponding to the distance between two contiguous contacts or banana" jacks on the board while, lengthwise of the transformer base they are spaced apart a distance double the distance between the contiguous banana? jacks; Figs. 3,3 and 3 show a simple two-terminal or two-plug mounting strip 84 on which: ismounted a resistor unit H. In this instance'themounting strip or'base has only two banana plugs- 82 spaced apart double-the distance between'the individual contacts in board 5|. An' instanceof a-three-plug unit is-shown-in Figs. 4; 4 and 4 where the mounting strip-.84 has three alined plugs 82 depending from its base with the plugs spaced apart a distance corresponding to the spacing'of' the banana jacks in the: board. In this instance the mounting strip carries an inductor: 83'. It will be appreciated that the**board isnot. limited. to use with." these component. parts only. Those shown and described: are merely given as examples, as com.- ponent parts of all varieties, chosenwith proper consideration as to physical size, may be used, more than four plugs being provided on mountingf strips for-"component parts if additional circuit contacts: or-mo're mechanicalsupportarfe required.

Using: the" designating numerals and letters, and referring toi'Fi'gs. 1,. Band 6 there is illustrated a circuit which is designated. as a. low gain direct coupled amplifier circuit. In setting up this. circuiton theboard, the following. component parts are arranged on the board as indicated in Fig.- 6, wherein eighteen connectors M are shown plugged in to connect the contacts BIB, DI B; EIG, GIS F1, F3; Fl l, F|3; G9,: GI Ii; H, J; JII, JIB'; J2'I, 'J2'3; LIE, LI'B'; M3,- M5; L9, N9; L10, Nll); Ml8, Ol8; N5, N1; NH, Nl3; 013, 015;: 09. Q9; and our, Q'H], lib-6L6 vacuum tube is indicated at A in's'ocket 30; a 6C5 vacuum tube at B in socket 30 a 50 ohml watt resistor C connects contacts: K1, -Ml; a 2000 ohm 5- watt resistor D connects contacts L9,; N9; a 50,000 ohm 1 watt resi'stor'E connects contacts Ll15 NI 5'; a 10,000 ohm 1 watt resistor Fconnects contacts N l-'6 P16; a 100,000 ohm- 1 watt resistor G connects contacts Kl l,"M| l-;"'a 500,000 ohm 1 watt resistor H connects contacts F4, F0; three 12 mfd, 4=50 "v. electrolytic condensers contacts J1, J9; 01, Q1 and OH, QH,- respectively; a crystal microphone or other high impedance signal source is plugged into contacts G3, G! as indicated at K and a loud speaker, including matchihg transformer is plugged intocentacts FEB; F22.

5. Figure 6 also indicates contacts M20, N20 as being connected to a power supply to furnish 6 volts A. C. and the power supply lines I2, 43 as connected to a 250 volts D. C. by contacts M22, M23. 'Ihe circuit thus established is shown diagrammatically in Fig. 6 but to simplify this illustration the eighteen connectors M and the connection between contacts M20, N20 and the tube sockets have been omitted. In this hook-up primary contacts are connected to the socket terminals asfollows: contacts 35 at J9, J I! are connected to the so-called No. 1 terminals of their respective sockets, these two terminals being indicated at IOI; contacts 40 at H9, H" are connected to the No. 3 terminals indicated at I03; contacts 30 at H8, I-IIB are connected to the No. 4 terminals indicated at I04; contacts 38 at H1, HIS are connected to the No. 5 terminals indicated at I05; contacts 3! atI'I, II5' are connected to the No. 6 terminals indicated at I06; and contacts 35 at J1, J I5 are connected to terminals No. 8 indicated at I08. This entire circuit is only. one of a multitude which can readily be arranged on the board. As with any other operative unit of electronic equipment, tests can be made with suitable instruments to determine correct operation or'abnormalties. Voltages and currents in various component parts or in the circuit can be checked, measured, or calculated; waveforms may be examined; defective parts or parts having electrical values differing from prescribed values may be substituted and the effects noted and troubleshooting practices developed. Again, component parts may be incorrectly assembled purposely for troubleshooting practice. Of course, when the various component parts are properly assembled, the hook-up will serve any function for which its commercial counterpart may be fitted.

Another circuit, using only one unit of the board, is as follows: Assuming that the tube sockets are connected in the same manner as just described in the previous example, 2. SEC vacuum tube is inserted in socket 30 two 12 mfd. 450 volt electrolytic condensers B are used to connect contacts J I, J3 and J5, J1; a 50,000 ohm 5 watt resistor C connects K1, K9 with polarity as indicated in Fig. '7; seven connectors D are plugged into contacts A9, C9; D9, F9; F6, F8; F3, H3; H4, J4; L9, N9 and 09, Q9; contacts F4, F5 are connected as indicated at E to a source of input power A. C. 110 to 120 volts, which in this instance is to be rectified; and a suitable output indicator or external load su h as a voltmeter or oscilloscope indicated at F is attached to contacts L'I, Q'I, at which point the rectified a d partially filtered D. C. output voltage is available for examination. This arrangement constitutes a low power full wave voltage double rectifier circuit using a single so ket or a single unit. Obviously, in addition to using single and double unit arrangements such as are disclosed herein, additional units can be provided on the board thus still further increasing the versatility of the latter.

As will be appreciated, the circuits or combinations that may be assembled on the present board with a relatively small assortment of component parts is practically unlimited, especially in view of the fact that as many duplicate units as are necessary or desirable can readily be provided. It will also be appreciated that persons with little or no knowledge of radio can readily assemble workable electronic circuits on the board by following comparatively simple information in the form of diagrams like those shown 6 in Figs. 6," 6 or '7, 7*. On the: other hand,.experienced-persons may utilize the board beneficially in developing troubleshooting and engineering practice. Also, as previously indicated, the board is capable of extensive use in class work in educational institutions.

It should be noted that the different groups of banana jacks or contacts on the board are preferably colored diiierently. In Fig. 1 the var ious contacts have been lined to designate colors,'the primary contacts and contacts 33, 34; being colored yellow for instance, while the contacts for the interconnector lines 41, 48, are colored green and the contacts or terminals 44 the positive power line 42 are coloredred and the terminals 45 in the negative power line 43 arezcolored black. All the other contacts may be white or otherwise colored. It is also advantageous to make the mounting strips 84 or the supporting bases of other component parts such as the base 19 of transformer 18 of a trans-' parent material. This use of colored contacts or terminals on the board and transparent mountings for the various component parts facilitates inspection of the board when the various instrumentalities are mounted therein for the purpose of determining the location of the latter or the banana jacks into which those component parts have been connected.

What I claim is:

1. A board for demonstrating electrical circuits comprising a panel of insulating material, a multi-terminal tube socket centrally located on said panel, a plurality of primary contacts arranged in longitudinal and transverse rows on said panel and forming a rectangular band surrounding said socket, each of said primary contacts being connected to a diiferent terminal of said socket, a multiplicity of secondary contacts on said panel arranged in equidistantly spaced longitudinal and transverse rows parallel to said rows of primary contacts so all of said contacts are equidistantly spaced from contiguous contacts, electrical connections between each of said primary contacts and neighboring secondary contacts forming primary groups of interconnected contacts in the area around said socket and respectively connected to the terminals thereof for connecting circuit components to said terminals, electrical connections between contacts in the outermost longitudinal and transverse rows of contacts, electrical connections between the next outermost longitudinal and transverse rows of contacts, said two connected outermost rows constituting positive and negative power lines extending around the margin of said panel, the secondary contacts between said primary groups and said power lines being arranged in connector groups, and electrical connections between the contacts in each connector group, each of said connector groups including one contact adjacent a contact in a primary group, one contact adjacent a contact in said power lines, and one contact adjacent a contact in another connector group for connecting circuit components to said primary groups and said power lines.

2. An apparatus for demonstrating diiferent radio circuit arrangements involving at least one multi-terminal tube and a plurality of conventional radio circuit components, such as resistors, condensers, rectifiers and the like, at least two separable connectors on each of said circuit components, the connectors of all of said components being in line and equidistantly spaced or spaced at one or more multiples of a selected accagcsu 1 unit of spacing" from each otl ier a;*-boar haw "thereon aatt least' one-mu=lti-termihal= tube socketancl aiplurality of component accommodating-contacts arranged in longitudinaland transverse rows of cor'itacts, adjacentones of said rows being-parallel and-spaced from each other -atwhe same unit distance as said connectorssthe contacts inthe areaof' the'boardflmmediatelysurroundingsaid socketbeing arranged pri'mary groups; electrical connections between the contacts of eachprimary group, electricalconnectionsfrom each primary group to adifferefit terminal 'on said socket, electrical connections between the contacts in the outermost longitudinal and transverse rows'around the marginal edge of the board, electrical connections betweenthe contacts in the nextoutermost longitudinal and transverse" rows around the'margin of the'board said connected inar-- glnal rows constituting positive and negative power lines, the-contacts in the'area betweensaid'primarygroups and said power lines being arranged i-n auxiliary groups, electrical-connec tions between the contactsof each auxiliary group, each of saidauxilia-ry groups including one contact adjacent-a, contact-in-aprimary group; one contact adjacent a contactin said power lines, and one contact adjacent a con-- 8': tact of another auxiliary group, whereby cliii ferent alternative circuit arrangements between said socket and said power line can be demonstrated on the board: by connecting the con nectors on said components to the contacts ot different groups onsaid board to form circuits between: said socket and" said power lines CHARLES E. BALLARD.

REFERENCES CITED The-following references are ofrecord in the file of thispatent:

UNITED- STRTES PATENTS Nui'nl o'e'r I Name Date FOREIGN PATENTS Nam e,r, Country 7 Date 16-11537 Switzerland July 1'?) 1933 {323;492 Great Eritain 1924 age-6w great Britain 1931; 571,411 'Ge'rn'iany Mar. 2, 1'9'33 OTHER REFERENCES R'befvifig' T1156" Manual, page 2, 1942 

